The present invention relates to control switches or actuators, in particular, to an optical sensing `joystick` wherein optical mask members selectively block opto-switch light communication in predetermined relationship to joystick position thereby providing a digital output representative thereof.
Joysticks are well known to the art and are particularly suited to control or direct movement of a device or symbol in two dimensions. In the video game field, for example, joysticks have been utilized to provide control input to the game enabling a player to direct movement of game symbols two-dimensionally across a conventional TV-type display screen.
Common joysticks utilize a plurality of switches, spaced generally in uniform fashion around the axis of the joystick control shaft, to register the displacement of the control stick in various predetermined directions. Generally four such switches, corresponding to the cardinal directions, are employed to detect a gross stick deflection in one of these directions or, where two adjacent switches are actuated simultaneously, at an angle therebetween. Simple joysticks of this type, although of limited initial cost, provide only gross directional control and include no deflection magnitude information whatsoever. As the respective directional switch is either closed or open, movement of the controlled object is necessarily restricted to a predetermined fixed velocity in the selected direction. This limited joystick capability is unacceptable for more complex systems where greater directional control and control over object velocity are required.
One solution includes the addition of a second actuator which controls the velocity of movement of an object in the direction selected by the joystick. This solution requires multiple control switch or actuator assemblies and, more importantly, generally requires two-handed operation. The joystick of the present invention, by contrast, provides for velocity as well as enhanced directional control in a single one-hand control.
Joysticks having combined direction and displacement encoding capability may be found within the art. Known examples included Bennett et al, U.S. Pat. No. 3,770,915; Hoke, U.S. Pat. No. 4,052,578; and Burson, U.S. Pat. No. 4,161,726. The above devices, however, are mechanically complex, and therefore too costly for some applications, for instance, the game market, and include mechanical displacement detection means subject to wear and consequent malfunction. It is known, that joysticks used in many applications are generally subject to extreme, rapid, and repeated control stick movements which can result in the premature failure of mechanical displacement detection means. For example, both Bennett '915 and Burson '726 utilize mechanical brushes or fingers adapted to engage metalized contacts on a surface moved in relation thereto. Both the brushes and contacts are prone to excessive wear and damage when subjected to the continuous harsh usage characteristic of the game environment. Hoke '578 utilizes a multi-cam arrangement to engage associated switches. Again, mechanical switch failure following prolonged harsh usage combined with the expense and complexity of the multiple cam and switch mechanism renders this device unattractive in the game market.
The instant joystick, by contrast, utilizes a novel optical-mask arrangement loosely retained for sliding motion and adapted to optically `switch` fixed mounted opto-switches. There are no critical sliding mechanical contacting surface or other mechanical switches such as found in the above patents. Nor is direct mechanical engagement or contact between respective moving and stationary joystick members required.
It is, therefore, an object of the present invention to provide a joystick that may be manufactured at reasonable cost as required for the game and other industries and is suited to use in harsh environments. The joystick preferably utilizes opto-switches to avoid mechanical actuating engagement and mechanical switches. Further, optical-mask members having fins thereon shall be retained for sliding movement with respect to the opto-switches. The switches and fins are spaced to provide discrete output codes uniquely corresponding to the displacement of the control column.